After same-sex marriage victory, the PM shifts his sights to 2018 and the economy

Liberal MP Warren Entsch hugs Australian Prime Minister Malcolm Turnbull after the passing of the Marriage Amendment Bill in the House of Representatives at Parliament House in Canberra, Thursday, December 7, 2017. (AAP Image/Lukas Coch) NO ARCHIVING

Liberal Member for North Sydney Trent Zimmerman and Prime Minister Malcolm Turnbull celebrate the passing of the Marriage Amendment Bill in the House of Representatives at Parliament House in Canberra, Thursday, December 7, 2017. (AAP Image/Mick Tsikas) NO ARCHIVING

Prime Minister Malcolm Turnbull has declared the economy will be the government's chief focus in 2018 after the passage of same-sex marriage cleared away an issue that has dogged the Coalition for most of the year.

During a media blitz on Friday morning, Mr Turnbull said he struggled to contain his emotion on Thursday when the parliamentary year ended by enshrining an overwhelming "affirmation" for LGBTI Australians, and young people "who are feeling uncertain and challenged".

The Parliament emphatically backed the bill to change the Marriage Act, with only four MPs voting against it and a handful of others abstaining. In emotional scenes, people in the public gallery sang I Am, You Are, We Are Australian and politicians waved rainbow flags.

In the presence of Mr Turnbull and Attorney-General George Brandis, Governor-General Sir Peter Cosgrove signed the bill into law on Friday morning. Same-sex couples will shortly be able to give the required 30 days notice and get married from January 9.

An emotional Senator Brandis said the scenes in Parliament House on Thursday were "unforgettable".

"It's a big thing," he told ABC radio.

"Of all the things that I've done since I've been in Parliament, I think this is the one that will be most consequential."

Mr Turnbull described the postal survey as a game-changer for the issue, now resolved after years of debate.

He criticised Labor for not progressing the matter when in office but said the victory now belongs to the whole Parliament.

The passage of the laws would not put religious freedoms at risk or traditional marriage, he insisted.

"People that think gay people making a commitment is is a threat to her marriage fails to realise that the real threat is lack of commitment," Mr Turnbull said.

The Prime Minister said his sights were now on the government's plans for tax, energy, education and childcare.

Asked what the big theme for 2018 would be, Mr Turnbull said: "It is more money in the pockets of hardworking Australian families and business. It's getting on with delivering the national energy guarantee. Getting on with our business tax cuts which are already delivering nearly 1,000 jobs a day - 85 per cent of them full-time, I might say - over the last year," Mr Turnbull told ABC radio.

He has foreshadowed personal income tax cuts ahead of the next election, although critics have warned the budget limits how large they can be.

Australia is the 26th country to legalise same-sex marriage. The change happened 13 years after former prime minister John Howard amended to Marriage Act to explicitly limit it to heterosexual couples.